part time CO2

[TomFromStLouis]

Okay, I know about turning off the CO2 at night (optional, but maybe a good idea to avoid pH swings and of course your CO2 tank lasts longer). So if you faithfully turned off the CO2 each night when the lights go off and on each morning, you have a good system running maybe 10-12 hours per day each and every day.

My tank is in my office, and since I am not around it on weekends, I am considering just using the CO2 injection while I am there, only 40 hours per week. Anybody do this? I suppose my CO2 levels will be lower overall, especially on Monday mornings :). Will this cause any stress for the plants on weekends when the lights are on and CO2 levels drop? I'd guess my toughest plant challenges are glossostygma and rotala wallichii; otherwise fairly easy growers I'd say.

In other words, will the inconsistancy of juicing my CO2 levels only weekdays cause any harm to the plants trying to grow? I am willing to live with less than maximum growth and am trying to avoid any CO2 disasters. Disasters? Like the near miss this weekend where I set the bubbles at 3 per second and came in the next day to find a deluge of CO2 coming through, a very stressed fish, aggressive pearling all around, and pH below 6.0; obviously something with the regulator burped - I do not want this risk without being around when my fish load is full.

Any thoughts and practical experience welcome.

[djlen]

You referred a couple of times to stressing the plants. I would not worry about the plants.....worry about the fish. I don't know your tank's water parameters, but my guess is that going from 3 bubbles/sec. to 0/sec. for the weekend, is going to cause a fairly large pH swing, and then the other way when you start it up again on Monday.
You need a more dependable needle valve from the sounds of it.
My suggestion is to lower your bubble rate, get a needle valve that will keep it consistent, and invest in a solenoid that will turn your CO2 off at night when your lights go out. You can put your lights on a timer as well to keep things consistent. And I would leave that set up go 7 days a week.
Just my humble opinion.....
Len

[TomFromStLouis]

I am worried about the fish, which is why I ask about not risking another episode. Two points:

I have read enough solenoid horror stories that I chose not to go that route. Plan A was to just leave the CO2 on at a moderately low rate at all times. This leads to pH swings from day to night, right? So Plan B is to reduce the swings by not injecting at night. As for the weekends, light with no CO2 shouldn't affect the pH much - I look for little pH volatility on the weekends. I thought this plan made sense for the fish as long as the plants do not mind. Please correct any part of this that is mistaken.

Secondly, I do have a quality needle valve (Clippard, I think). I just left the setup after setting it for the first time and I think the regulator pressure 'adjusted' after being on for a while or something. Why the needle valve did not keep the bubble count at 3 per second I do not know. I need to gain confidence in this whole system for me to return to Plan A.

My original pre-CO2 parameters were pH = 7.2, KH = 3.5, so ambient CO2 was about 7?

[Skittyfish]

I ran out of CO2 (pressurized due to unknown leak). In one day my pH went from 6.4 to 7.6:eek: . The fish seem o.k., but algae has already sprung up and out!. I would think the same thing would happen over a weekend. I will get my CO2 going again tomorrow and by then it will have been three full days.

So, if algae and pH rise in only a day and a half then I think you will definately have problems.

[nvision]

i usually release my co2 conservatively... just enough so that plants are doing well and keeping algae at bay. this method allows me to run the gas continuously with minimal fuss.

regarding the needle valve releasing too much co2 abruptly, maybe it's the change in pressure within. if your cannister is new or has just been refilled, let it equalize in the room before using it. and even then, monitor the pressure closely because it may take up to a few days for it to become truly constant. hope this help.

[djlen]

You're going to get far less of a pH swing by running at a lower bubble count 24/7 than with all the on and off stuff. For a 3.5kH you should be shooting of a 6.7pH, which would give you almost 21ppm CO2. I would find the bubble rate that gives you that pH and let it run. I run pressurized and have never had more than a one point swing when leaving it run all night.
If you're asking for what we think is best for the fish and the plants, that's my opinion.
Len

[TomFromStLouis]

Len, I appreciate your patient and thorough responses. I apparently do not fully understand CO2 and pH swings like I thought I did. I will leave it on for a while and see how it goes.